Fe3O4/RGO-Ionic liquid Nanocatalyst as Amplifier for Fabrication of Highly Sensitive Electrochemical Sensor in Monitoring of Thallium Environmental Fluids

The analysis of Tl(I) is essential due to its high toxicity, environmental persistence, and potential to cause neurotoxic and carcinogenic effects even at trace levels. In this work, a reduced graphene oxide–magnetite nanocomposite (rGO–Fe₃O₄) combined with the ionic liquid N -butyl-3-methylimidazolium tetrafluoroborate (N-B-3-MITFB) was used to modify a carbon paste electrode. The resulting rGO–Fe₃O₄/N-B-3-MITFB/CPE was employed for the sensitive detection of Tl(I) in aqueous samples. The electrochemical characteristics of the sensor were systematically investigated using differential pulse anodic stripping voltammetry (DPASV). This electrode demonstrated strong oxidative activity for Tl(I) at a lower overvoltage (compared to unmodified electrodes), along with a higher current response and enhanced sensitivity. Under optimal conditions (pH 7, accumulation time 400 s, scan rate of 30 mV·s⁻¹), the calibration curve for Tl(I) exhibited a linear range of 0.07–420 µM with a limit of detection (LOD) of 0.9 nM. The proposed sensor displayed excellent selectivity for determining Tl(I) levels in the presence of common interfering species (e.g., Pb²⁺, Cr²⁺, Cu²⁺, NO₃⁻). The rGO-Fe3O4/N-B-3-MITFB/CPE showed high analytical performance for Tl(I) analysis in diverse water samples (e.g.,drinking water, well water, and waste water), achieving recoveries of 97.5–102.4%.